U.S. patent application number 11/926975 was filed with the patent office on 2009-04-30 for minimally invasive interbody device and method.
This patent application is currently assigned to ZIMMER SPINE, INC.. Invention is credited to Hugh D. Hestad, Robert Garryl Hudgins, John Maertens.
Application Number | 20090112323 11/926975 |
Document ID | / |
Family ID | 40259165 |
Filed Date | 2009-04-30 |
United States Patent
Application |
20090112323 |
Kind Code |
A1 |
Hestad; Hugh D. ; et
al. |
April 30, 2009 |
MINIMALLY INVASIVE INTERBODY DEVICE AND METHOD
Abstract
The present invention relates to methods and devices for
insertion between adjacent vertebrae in a spine following removing
at least a portion of a nucleus from within a disc. In one
embodiment, the device comprises a member having a flexible wall
surrounding an internal volume and a coupler that is secured to the
flexible wall. The member is adapted to expand when filled with a
first filler material to form an interior cavity. The coupler has a
first access point, a second access point, a first coupler side
hole, and an optional second coupler side hole. The first and
second access points are adapted to removably receive one or more
fill tubes. The fill tubes cooperate with the first and optional
second coupler side holes to direct the first filler material into
the internal volume and a second filler material into the interior
cavity.
Inventors: |
Hestad; Hugh D.; (Edina,
MN) ; Hudgins; Robert Garryl; (Monticello, MN)
; Maertens; John; (Chanska, MN) |
Correspondence
Address: |
CROMPTON, SEAGER & TUFTE, LLC
1221 NICOLLET AVENUE, SUITE 800
MINNEAPOLIS
MN
55403-2420
US
|
Assignee: |
ZIMMER SPINE, INC.
Minneapolis
MN
|
Family ID: |
40259165 |
Appl. No.: |
11/926975 |
Filed: |
October 29, 2007 |
Current U.S.
Class: |
623/17.12 ;
606/279 |
Current CPC
Class: |
A61F 2/4611 20130101;
A61F 2/441 20130101; A61F 2002/30586 20130101; A61F 2002/30884
20130101; A61F 2002/302 20130101; A61F 2002/30593 20130101; A61F
2230/0065 20130101 |
Class at
Publication: |
623/17.12 ;
606/279 |
International
Class: |
A61F 2/44 20060101
A61F002/44; A61B 17/88 20060101 A61B017/88 |
Claims
1. An interbody device adapted for insertion between adjacent
vertebrae in a spine, the device comprising: a member having a
flexible wall surrounding an internal volume, the member being
adapted to expand when filled with a first filler material to form
an interior cavity; and a coupler secured to the flexible wall, the
coupler having a first access point, a second access point, a first
coupler side hole, and an optional second coupler side hole,
wherein the first and second access points are adapted to removably
receive one or more fill tubes that cooperate with the first and
optional second coupler side holes to direct the first filler
material into the internal volume and that cooperate to direct a
second filler material into the interior cavity.
2. The device of claim 1 further including a keel projecting
axially from the member, the keel being adapted to fill with the
first filler material and cooperate with a channel machined in the
adjacent vertebrae.
3. The device of claim 2 wherein the coupler further includes a
third access point, and wherein the second access point opposes the
third access point and the second and third access points are
adapted to direct the second filler material into the interior
cavity.
4. The device of claim 1 further including a plurality of endplate
anchors attached to the flexible wall, the endplate anchors being
adapted to engage an endplate of the adjacent vertebrae.
5. The device of claim 1 wherein the first filler material
comprises a first elastomeric material and the second filler
material comprises a second elastomeric material that is more
elastic than the first elastomeric material.
6. The device of claim 1 wherein the coupler comprises a rigid
material.
7. The device of claim 1 further including a dual lumen fill tube
defining a first passage and a second passage, the dual lumen fill
tube being adapted to removably cooperate with both the first
access point and the second access point, such that when the dual
lumen fill tube is inserted into the coupler, a member fill opening
at a distal end of the dual lumen fill tube is in fluid
communication with the internal volume via the first passage and
the first and, optionally, second coupler side holes, and a cavity
fill opening at the distal end is in fluid communication with the
interior cavity via the second passage and the second access
point.
8. The device of claim 1 wherein the first access point is coaxial
with the second access point, the first coupler side hole opposes
the optional second coupler side hole, and the first and optional
second coupler side holes are oriented transverse to the first and
second access point.
9. The device of claim 8 wherein the coupler further includes an
annular flange comprising a diameter of the second access point
that is less than a diameter of the first access point, the annular
flange being adapted to prevent tube penetration into the interior
cavity.
10. The device of claim 1, wherein a top and a bottom wall enclose
the interior cavity.
11. An orthopedic system adapted for insertion between adjacent
vertebrae in a spine, the system comprising: a member having a
flexible wall surrounding an internal volume, the member being
adapted to expand when filled with a first filler material thereby
forming an interior cavity; a coupler secured to the flexible wall,
the coupler having a first access point, a second access point, a
first coupler side hole, and an optional second coupler side hole
adapted to removably receive one or more fill tubes that cooperate
with the first and optional second coupler side holes to direct the
first filler material into the internal volume and that cooperate
to direct a second filler material into the interior cavity; a
member fill tube defining a first passage and adapted for removable
cooperation with the coupler via the first access point such that
when the member fill tube is inserted into the coupler, an opening
at a distal end of the member fill tube is in fluid communication
with the internal volume via the first passage, the first coupler
side hole, and the optional second coupler side hole; and a cavity
fill tube defining a second passage and adapted for removable
cooperation with the coupler via the first access point and the
second access point such that when the cavity fill tube is inserted
into the coupler, an opening at a distal end of the cavity fill
tube is in fluid communication with the interior cavity via the
second passage and the second access point.
12. The system of claim 11 wherein the coupler includes an annular
flange adapted to cooperate with the cavity fill tube such that
when the cavity fill tube is inserted through the first access
point, the distal end of the cavity fill tube abuts the annular
flange.
13. The system of claim 11 wherein the coupler further includes a
third access point, and wherein the second access point opposes the
third access point and the second and third access points are
adapted to direct the second filler material into the interior
cavity.
14. The system of claim 11 further including a plurality of
endplate anchors attached to the flexible wall, the endplate
anchors being adapted to engage an endplate of the adjacent
vertebrae.
15. The system of claim 14 wherein the first filler material
comprises a first elastomeric material and the second filler
material comprises a second elastomeric material that is more
elastic than the first elastomeric material.
16. The system of claim 11 wherein the coupler comprises a rigid
material.
17. A method of treating a spine following forming an incision in
an annulus of a disc between adjacent vertebrae and removing at
least a portion of a nucleus from within the disc to form a space
surrounded by the annulus, the method comprising: placing an
interbody device within the disc space, the interbody device
comprising: a member having a flexible wall surrounding an internal
volume, the member being adapted to expand when filled with a first
filler material to form an interior cavity; and a coupler secured
to the flexible wall, the coupler having a first access point, a
second access point, wherein the first and second access points are
adapted to removably receive one or more fill tubes that cooperate
with a first and an optional second coupler side holes to direct
the first filler material into the internal volume and that
cooperate to direct a second filler material into the interior
cavity; filling the internal volume with the first filler material,
the first filler material comprising a first elastomeric material;
and filling the interior cavity with the second filler material,
the second filler material comprising a second elastomeric
material, wherein the second elastomeric material is more elastic
than the first elastomeric material.
18. The method of claim 17 further comprising: providing the first
filler material through the first access point, the first coupler
side hole, and the optional second coupler side hole into the
internal volume, thereby expanding the member to form the interior
cavity bordered by the member; and providing the second filler
material through both the first access point and the second access
point into the interior cavity, wherein upon hardening of the
second filler material, the adjacent vertebrae are substantially
fused to one another.
19. The method of claim 17 wherein filling the internal volume
includes providing a member fill tube in removable cooperation with
the coupler, wherein the member fill tube cooperates with the first
access point and a portion of the member fill tube substantially
blocks the second access point such that while filling the member,
the first filler material passes through the member fill tube,
through the first access point, through one or both of the first
and the optional second coupler side holes, and into the internal
volume.
20. The method of claim 19 wherein filling the interior cavity
includes withdrawing the member fill tube from the coupler and
inserting a cavity fill tube into the coupler such that a portion
of the cavity fill tube substantially blocks the first access point
and the second access point, whereby providing the second filler
material includes providing the second filler material through the
cavity fill tube, through the first access point, through the
second access point, and into the interior cavity.
21. The method of claim 20 wherein inserting the cavity fill tube
into the coupler includes inserting the cavity fill tube until the
cavity fill tube abuts an annular flange proximate the second
access point.
22. The method of claim 17 further including forming a first
channel in an endplate of an upper-adjacent vertebra and forming a
second channel in an endplate of a lower-adjacent vertebra prior to
placing the member, wherein the member has an upper keel and a
lower keel that axially project from the member within the disc
space, such that during filling the internal volume of the member,
the upper keel expands into the first channel and the lower keel
expands into the second channel.
23. The method of claim 17 wherein filling the internal volume of
the member causes a plurality of endplate anchors to contact at
least one endplate of the adjacent vertebrae.
24. The method of claim 17 wherein filling the internal volume and
filling the interior cavity includes providing the first filler
material and the second filler material, respectively, through a
dual lumen fill tube comprising a first passage in fluid
communication with the internal volume and a second passage in
fluid communication with the interior cavity, whereby the first
filler material passes through the first passage and into the
internal volume, and the second filler material passes through the
second passage and into the interior cavity.
25. The method of claim 17 further comprising: providing a
containment barrier for the second filler material.
Description
FIELD OF THE INVENTION
[0001] This invention relates to orthopedic implants, and, more
particularly, to interbody spinal devices.
BACKGROUND OF THE INVENTION
[0002] A spine includes a series of joints or motion segments. The
components of each motion segment include two adjacent vertebrae,
their apophyseal joints, an intervertebral disc, and connecting
ligamentous tissue. Each motion segment is capable of flexion,
extension, lateral bending, and translation. Each component of the
motion segment contributes to these capabilities and to the
mechanical stability of the spine.
[0003] The intervertebral disc is one component that facilitates
spine motion by allowing slight relative movement between adjacent
intervertebral discs as well as holding the vertebrae together. The
discs comprise an outer annulus fibrosus which surrounds and
contains a nucleus pulposus. The nucleus acts as a shock absorber
and a spacer to separate adjacent vertebra. In a healthy spine, the
motion segments, including the discs, collectively enable the
familiar kinematics of the spinal column. However, degeneration of
the disc can cause great and sometimes debilitating pain.
[0004] For example, radicular pain in the lower extremities is
often a symptom of a herniated disc. A herniated disc is
characterized by rupture of or tear in the annulus fibrosus which
permits a portion of the nucleus to extrude therefrom. If the
nucleus extrudes in proximity to the numerous nerves surrounding
the spine, the pressure, or the mere contact, of the nucleus on the
nerves may cause severe pain. In addition, axial pain is often a
symptom of degenerative disc disease. Degenerative disc disease is
generally associated with dehydration of the nucleus that occurs
with age. When the nucleus dehydrates, it loses its ability to
absorb shock, which may lead to axial pain.
[0005] Treatment methods for repair of disc disorders include
spinal fusion. One type of spinal fusion procedure requires
resection of a portion of the disc. The procedure for removing a
portion of the disc is known as a discectomy. Once a portion of the
disc is removed, another material or device is inserted into the
space created to stabilize the spinal column. There are a variety
of devices available for insertion into the disc space. For
example, one fusion procedure includes placing a cage between and
in contact with the vertebra and packing the cage with graft
material. The graft material may bond with the endplates of the
adjacent vertebra thus fusing the vertebra together. However, these
types of devices require significant retraction of tissue to allow
the surgeon sufficient access to the disc and to insert the device
into the corresponding disc space. Consequently, patient recovery
time may be significant simply because of the invasiveness of these
procedures.
[0006] Thus, devices and methods for spinal fusion that are stable,
yet minimally invasive, are needed.
SUMMARY OF THE INVENTION
[0007] The present invention provides an interbody device adapted
for insertion between adjacent vertebrae in a spine. In one
embodiment, the device comprises a member having a flexible wall
surrounding an internal volume and a coupler. The member is adapted
to expand when filled with a first filler material to form an
interior cavity. The coupler is secured to the flexible wall. The
coupler has a first access point, a second access point, a first
coupler side hole, and an optional second coupler side hole. The
first and second access points are adapted to removably receive one
or more fill tubes. The fill tubes cooperate with the first and
optional second coupler side holes to direct the first filler
material into the internal volume and a second filler material into
the interior cavity.
[0008] In accordance with another aspect of the invention, an
orthopedic system is provided. The orthopedic system is adapted for
insertion between adjacent vertebrae in a spine. In one embodiment,
the system comprises a member having a flexible wall surrounding an
internal volume and a coupler secured to the flexible wall. The
member is adapted to expand when filled with a first filler
material to form an interior cavity. The coupler has a first access
point, a second access point, a first coupler side hole, and an
optional second coupler side hole adapted to removably receive one
or more fill tubes. The fill tubes cooperate with the first and
optional second coupler side holes to direct the first filler
material into the internal volume and that cooperate to direct a
second filler material into the interior cavity.
[0009] In another embodiment, a member fill tube defines a first
passage and is adapted for removable cooperation with the coupler
via the first access point. When the member fill tube is inserted
into the coupler, an opening at a distal end of the member fill
tube is in fluid communication with the internal volume via the
first passage, the first coupler side hole, and the optional second
coupler side hole. In a related embodiment, a cavity fill tube
defines a second passage. The cavity fill tube is adapted for
removable cooperation with the coupler via the first access point
and the second access point. When the cavity fill tube is inserted
into the coupler, an opening at a distal end of the cavity fill
tube is in fluid communication with the interior cavity via the
second passage and the second access point.
[0010] In accordance with another aspect of the invention, a method
of treating a spine is provided. The method follows forming an
incision in an annulus of a disc between adjacent vertebrae and
removing at least a portion of a nucleus from within the disc to
form a space surrounded by the annulus. The method comprises
placing the interbody device within the disc space and then filling
the internal volume with the first filler material. In one
embodiment, the first filler material comprises a first elastomeric
material. Following filling the internal volume, filling the
interior cavity with a second filler material. In another
embodiment, the second filler material comprises a second
elastomeric material. In yet another embodiment, the second
elastomeric material is more elastic than the first elastomeric
material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention and, together with a general description of the
invention given above, and the detailed description given below,
serve to explain the invention.
[0012] FIG. 1 is a perspective view of one embodiment of an
interbody device shown with an member in an expanded state;
[0013] FIG. 2 is a plan view of the interbody device of FIG. 1 with
a partial cross section of a coupler and the member;
[0014] FIGS. 3 and 4 are elevation views of embodiments of a member
fill tube and a cavity fill tube, respectively, with partial cross
sections of a proximal end of each;
[0015] FIGS. 5 and 6 are enlarged partial cross sections of the
member fill tube of FIG. 3 and the cavity fill tube of FIG. 4,
respectively, each individually inserted into the coupler of FIG.
2;
[0016] FIG. 7 depicts a cross-sectional view taken along a
transverse plane through an intervertebral disc illustrating a
delivery cannula inserted therein for delivery of one embodiment of
the interbody device with the member shown wrapped around a
coupler;
[0017] FIG. 8 depicts one method of placing an interbody device
within the disc of FIG. 7;
[0018] FIG. 9 depicts one method of providing a first filler
material into the member of FIG. 8;
[0019] FIG. 10 depicts one method of providing a second filler
material within the member following providing the first filler
material of FIG. 9;
[0020] FIG. 11 depicts one embodiment of the interbody device of
FIG. 10 following removal of the delivery cannula and closure of
the incision in the annulus;
[0021] FIG. 12 depicts a cross-sectional view taken along a
sagittal plane through a spine illustrating one embodiment of the
interbody device placed within a disc and following injection of
the first filler material and the second filler material
therein;
[0022] FIG. 13 depicts an enlarged, partial cross section of an
embodiment of a dual lumen fill tube inserted into the embodiment
of the coupler of FIG. 2;
[0023] FIG. 14 is a perspective view of another embodiment of the
interbody device having a keel contiguously formed with the
member;
[0024] FIG. 15 is a plan view of the interbody device of FIG. 14
with a partial cross section of another embodiment of the coupler
and the member;
[0025] FIG. 16 depicts a cross-sectional view taken along a
sagittal plane through a spine with the embodiment of the interbody
device of FIG. 14 placed within a disc and following injection of
the first filler material and the second filler material;
[0026] FIG. 17 is a perspective view of another embodiment of the
interbody device having a plurality of endplate anchors secured to
the member thereof; and
[0027] FIG. 18 is a perspective view of one embodiment of an
interbody device shown with a member in an expanded state.
DETAILED DESCRIPTION
[0028] FIGS. 1 and 2 depict one embodiment of an interbody device
10 of the present invention. As shown, the interbody device 10
comprises a member 12 and a coupler 14. As will be discussed in
detail later with reference to FIGS. 7-11, following a partial
discectomy, the interbody device 10 is placed between adjacent
vertebrae. Once placed, tubes (embodiments of which will be
described herein) configured to removably cooperate with the
coupler 14 may be used to fill the member 12 with material. In one
embodiment, the interbody device 10 facilitates stabilization of a
spine and also facilitates stabilization of adjacent vertebrae.
[0029] To that end, with reference once again to FIG. 1, the
interbody device 10 with the member 12, shown in an expanded state,
provides an anatomically contoured shape. While the interbody
device 10 has a nearly ring-like perimeter, other shapes and
configurations are possible. By way of example and not limitation,
the interbody device 10 may be a customized shape designed to
accommodate the patient's anatomy, particularly a shape that will
treat the patient's physiological problem. Not only may the
interbody device 10 have a multitude of shapes, a thickness or
height H of the member 12 after it is expanded may vary around its
perimeter. For instance, the interbody device 10 may form a
wedge-like shape when expanded. Therefore, the interbody device 10
may conform more readily to the patient's anatomy or may facilitate
a particular treatment, e.g., the interbody device 10 may be
designed to treat degenerative disc disease, stenosis,
spondylolisthesis, or other disorder.
[0030] With reference to FIG. 2, in one embodiment, the member 12
has a ring-like or annular shape having a flexible wall 16. The
flexible wall 16 surrounds an internal volume 18, as shown in the
partial cut-away view in FIG. 2. The flexible wall 16 may comprise
a polyester, such as Dacron.TM.; a polymethylmethacrylate; a
metallic, woven fabric made of titanium, one of its alloys, or a
stainless steel; or other suitable biologically compatible
material. In one embodiment, the flexible wall 16 is woven,
knitted, or braided. Therefore, the annular member 12 may excrete a
portion of materials injected therein, as the annular member 12 is
expanded to form an interior cavity 19.
[0031] As shown in FIG. 2, the coupler 14 is attached to the
flexible wall 16. It will be appreciated that the coupler 14 may be
attached to the flexible wall 16 via mechanical crimp or clamp,
thermal or weld bond, adhesive, or other bonding method known in
the art. The coupler 14 may be configured as a tube-like structure
to facilitate minimally invasive insertion, as described in detail
with regard to FIG. 7. Returning to FIG. 2, the coupler 14 has a
first access point 20, a second access point 22, a first coupler
side hole 24, and a second coupler side hole 26. In an exemplary
embodiment, the first access point 20 is coaxial with the second
access point 22. In yet another embodiment, the first coupler side
hole 24 opposes the second coupler side hole 26 and both the first
and second coupler side holes 24, 26 are orientated transverse to
the first and second access points 20, 22.
[0032] The access points 20, 22 and side holes 24, 26 cooperate
with tubes for directing material within the interbody device 10.
For example, as shown in FIGS. 3 and 4, a member fill tube 28 and a
cavity fill tube 30, respectively, may be used to direct materials
to the coupler 14 for distribution within the annular member 12.
Thus, according to another aspect of the present invention and an
exemplary embodiment, an orthopedic system comprises the interbody
device 10 of FIG. 1, the member fill tube 28 of FIG. 3, and the
cavity fill tube 30 of FIG. 4. As shown in FIGS. 5 and 6, which
will be discussed in detail below, the first access point 20
slidably receives either the member fill tube 28 of FIG. 3 or the
cavity fill tube 30 of FIG. 4, respectively.
[0033] In one embodiment, the coupler 14 comprises a rigid
material, such as a biocompatible, thermoplastic polymer or
biocompatible metal or other similar material. The rigid material
does not sag or collapse when the member fill tube 28 is removed
from the coupler 14 prior to insertion of the cavity fill tube 30.
In other words, the coupler 14 remains open sufficient to receive
either tube 28, 30. The rigid material may also ease slidable
engagement and removal of the cavity fill tube 30 or reengagement
of the member fill tube 28 or cavity fill tube 30 should the
surgeon determine that the annular member 12 requires additional
material.
[0034] In another embodiment, as shown most clearly in FIGS. 5 and
6, the coupler 14 has an annular flange 32. The annular flange 32
may project from the coupler 14 proximate the second access point
22. As shown in FIGS. 5 and 6, in one embodiment, the annular
flange 32 may form the second access point 22. One skilled in the
art will appreciate that the annular flange 32 may have other
configurations, such as one or more protrusions on the coupler 14
that cooperate with one or more depressions on one or both of tubes
28, 30.
[0035] With reference to FIGS. 3 and 5, one embodiment of the
member fill tube 28 is illustrated in FIG. 3 for directing a filler
material into the internal volume 18 within the interbody device
10, as shown in FIG. 5. As shown in FIG. 3, the member fill tube 28
defines a first passage 34 that extends from a distal end 36 to a
proximal end 38. The distal end 36 of the member fill tube 28 has
an opening 40 formed concentrically with the longitudinal axis of
the tube 28 for introducing a filler material into the member fill
tube 28. A first tube side hole 42 and a second tube side hole 44
are formed proximate to the proximal end 38, for example transverse
to the longitudinal axis. As shown, in one embodiment of the member
fill tube 28, the proximal end 38 is closed.
[0036] With reference to FIG. 5, the member fill tube 28 is
removably inserted into the coupler 14 via the first access point
20. When the member fill tube 28 is positioned within the coupler
14, the first and second tube side holes 42, 44 at least partially
align with the first coupler side hole 24 and the optional second
coupler side hole 26, respectively. It will be appreciated that the
first and second tube side holes 42, 44 as well as the first and
second coupler side holes 24, 26 may have different configurations
and still facilitate flow of materials from the opening 40 into the
internal volume 18. The member fill tube 28 may also substantially
block the second access point 22 e.g., with the closed proximal end
38 when the other holes 24, 26, and 42, 44, respectively, are
aligned.
[0037] In one embodiment, the member fill tube 28 passes through
the first access point 20 and docks with the second access point
22. In other words, a portion of the member fill tube 28 cooperates
with a portion of the coupler 14. For example, the member fill tube
28 may have the proximal end 38 configured, as shown in FIG. 5, to
cooperate with the annular flange 32 projecting from the coupler
14. The cooperative engagement between the annular flange 32 and
the proximal end 38 of the member fill tube 28 may provide a
tactile "docking" sensation which the surgeon may identify as the
proper alignment of the member fill tube 28 within the coupler 14.
Proper alignment may include alignment of first and second tube
side holes 42, 44 with first and second coupler side holes 24, 26,
respectively. Furthermore, the member fill tube 28 has a length
that may extend to an accessible location outside the patient to
ease filling of the internal volume 18.
[0038] Similarly, one embodiment of the cavity fill tube 30 is
illustrated in FIG. 4 for directing a filler material into the
interior cavity 19 within the interbody device 10, as shown in FIG.
6. As shown, the cavity fill tube 30 defines a second passage 46
that extends from a distal end 48 to a proximal end 50. The distal
end 48 of the cavity fill tube 30 has an opening 52 therein for
introducing filler material into the cavity fill tube 30, and an
axial port 54 is formed in the proximal end 50. Thus the opening 52
is in fluid communication with the axial port 54 via the second
passage 46.
[0039] With reference to FIG. 6, in the embodiment shown, the
cavity fill tube 30 removably and slidably cooperates with the
first and second access points 20, 22 in the coupler 14. When the
cavity fill tube 30 is positioned within the coupler 14, as shown,
the axial port 54 provides fluid communication between the opening
52 and the interior cavity 19 via the second passage 46.
Furthermore, the cavity fill tube 30 blocks the first and second
coupler side holes 24, 26. In one embodiment, the cavity fill tube
30 passes through the first access point 20 and docks with the
second access point 22. In other words, a portion of the cavity
fill tube 30 cooperates with a portion of the coupler 14 to align
the axial port 54 with the second access point 22 in the coupler
14. For example, the cavity fill tube 30 may have the proximal end
50 configured, as shown in FIG. 6, similar to the proximal end 38
of the member fill tube 28 in FIG. 3, to cooperate with the annular
flange 32 projecting from the coupler 14. Similar to the member
fill tube 28, the cooperative engagement between the annular flange
32 and the proximal end 50 of the cavity fill tube 30 may provide a
tactile sensation which the surgeon may identify as the proper
alignment of the cavity fill tube 30 with the coupler 14.
Furthermore, the cavity fill tube 30 has a length such that the
distal end 48 may extend to an accessible location outside the
patient.
[0040] With reference generally to FIGS. 7-11, one method of using
the system or treating a spine is illustrated. As one skilled in
the art will appreciate, a discectomy involves resection of a
portion of a nucleus 56 via an incision 58 made in an annulus 60 of
a disc 62 thereby creating a disc space 64. With reference to FIG.
7, the method includes placing one embodiment of the interbody
device 10 within the disc space 64. By way of example, in one
embodiment of the system, a delivery cannula 66 is inserted through
the incision 58 and into the disc space 64. The interbody device 10
with the member fill tube 28 inserted into the coupler 14 is
inserted either simultaneously with the delivery cannula 66 through
the incision 58 or following initial insertion of the delivery
cannula 66 through the incision 58, i.e. as a separate insertion
step. The coupler 14 and annular member 12 may cooperate somewhat
like a trocar, known in the art, to ease passage of the coupler 14,
annular member 12, and delivery cannula 66 through the incision 58.
The coupler 14 and annular member 12 may also pass through the
delivery cannula 66 into the disc space 64. It will be appreciated
that the annular member 12 may be folded, wrapped, or otherwise
configured for insertion through the delivery cannula 66.
[0041] With reference now to FIG. 8, the annular member 12 in an
unexpanded state is unfolded within the disc space 64. Once placed,
and with reference to FIG. 9, a first filler material 68 is
injected into the opening 40 in the distal end 36 (not shown) of
the member fill tube 28. The first filler material 68 passes
through the first passage 34 through the coupler 14 and into the
internal volume 18 of the annular member 12 (one possible flow
pattern is illustrated in FIG. 9). While FIG. 9 clearly illustrates
flow of the first filler material 68 through both sides of the
coupler 14, that is through aligned holes 24, 42 and 26, 44 (shown
in FIG. 5), it will be appreciated that only one coupler side hole
24 or 26 may permit injection of the first filler material 68 into
the internal volume 18. In another embodiment, the annular flange
32 shown most clearly in FIG. 5, may prevent the first filler
material 68 from being accidentally injected into the interior
cavity 19 should the member fill tube 28 be accidentally removed
following insertion of the delivery cannula 66, annular member 12,
and member fill tube 28 through the incision 58 and thus requiring
reinsertion of the member fill tube 28. Expanding the annular
member 12 may facilitate distraction of adjacent vertebrae and
possibly decompression. The degree of distraction may depend upon
the pressure used to inject the first filler material 68 and the
material of the flexible wall 16. Also, as previously noted, the
annular member 12 may excrete a portion of the first filler
material 68. Therefore, if the annular member 12 contacts the
endplates 70, 72 of the adjacent vertebrae 74, 76 as shown in FIG.
12, the first filler material 68 may facilitate bonding of the
annular member 12 to the endplates 70, 72.
[0042] Returning to FIG. 9, once the annular member 12 is
sufficiently filled, the interior cavity 19 is formed. The member
fill tube 28 may then be withdrawn. During withdrawal of the member
fill tube 28, the coupler 14 may cooperate with the member fill
tube 28 to substantially prevent the first filler material 68 from
entering the coupler 14. In other words, any residual first filler
material 68 within the member fill tube 28 may be prevented from
building up within the coupler 14. In one method, once the member
fill tube 28 is withdrawn from the coupler 14, the first filler
material 68 may then be hardened or permitted to harden. In another
embodiment, the first filler material 68 is an elastomeric material
that may or may not harden following placement of the fill material
68 into the internal volume 18.
[0043] In another method, the first filler material 68 is an
in-situ curable material that hardens prior to removal of the
member fill tube 28. The coupler 14 may aid removal therefrom by
limiting contact of the fill material 68 with the member fill tube
28. Thus, slight movement, e.g., rotation, of the member fill tube
28 may break any connectivity between the in-situ curable first
filler material 68 and the member fill tube 28.
[0044] By way of example and not limitation, the first filler
material 68 may include bioresorbable materials; elastic materials,
such as, polyurethane, silicone rubber, in-situ curable polymer
(most likely an elastomer), and PVA (polyvinyl alcohol) hydrogel;
or other hydrogels, or may comprise poly(lactic acid),
poly(glycolic acid), p-dioxanone fibers, polyarylethyl,
polymethylmethacrylate, polyurethane, amino-acid-derived
polycarbonate, polycaprolactone, aliphatic polyesters, calcium
phosphate, unsaturated linear polyesters, vinyl pyrrolidone,
polypropylene fumarate diacrylate, polymethylmethacrylate (PMMA),
bis-GMA polymer, hydrogel polyurethane, polyacrylamides, a hydrogel
or combinations thereof, or other biologically compatible polymer
capable of supporting axial loads transmitted through the spinal
column.
[0045] In one method, once the member fill tube 28 in FIG. 9 is
withdrawn from the coupler 14, the cavity fill tube 30 may be
inserted into the coupler 14, as shown in FIG. 10. The coupler 14
may also aid in the insertion of the cavity fill tube 30 by keeping
the first access point 20 free of the first filler material 68. In
another embodiment, the annular flange 32, best shown in FIGS. 5
and 6, may prevent the cavity fill tube 30 from being thrust into
the interior cavity 19 and potentially rupturing the flexible wall
16. Once the cavity fill tube 30 is inserted into the coupler 14, a
second filler material 80 is injected into the opening 52 in the
distal end 48 (not shown) of the cavity fill tube 30. The second
filler material 80 passes through the second passage 46, through
the coupler 14, and into the interior cavity 19. In one embodiment,
the second filler material 80 fills the interior cavity 19 formed
by the interbody device 10 to contact each endplate 70, 72 of each
vertebrae 74, 76, as shown in FIG. 12.
[0046] As previously described, the cavity fill tube 30 is inserted
into the delivery cannula 66 to engage the coupler 14, usually
without visual assistance, though guide wires (not shown) may
assist the surgeon in inserting the cavity fill tube 30 into the
coupler 14. In those instances where no visual assistance is
available, the annular flange 32, shown most clearly in FIG. 6, may
provide some tactile sensation that the cavity fill tube 30 has
seated within the coupler 14. The annular flange 32 may prevent the
surgeon from inadvertently inserting the cavity fill tube 30 and
damaging the annular member 12. Alternatively, since the surgeon is
expecting the cavity fill tube 30 to seat within the coupler 14,
the lack of the docking or seating sensation may prevent the
surgeon from inadvertently injecting the second filler material 80
into the disc space 64. As with removal of the member fill tube 28
in FIG. 5, one skilled in the art will appreciate that the coupler
14 may ease withdraw of the cavity fill tube 30 by substantially
preventing the first filler material 68 from contaminating the
cavity fill tube 30 if the first filler material 68 has not
sufficiently hardened prior to its removal.
[0047] As shown in FIG. 11, the cavity fill tube 30 is removed once
the interior cavity 19 is filled with the second filler material
80. The delivery cannula 66 is also removed. The incision 58 in the
annulus 60, as well as other necessary incisions in the surrounding
tissue, are closed. FIGS. 7-11 illustrate a posterior entry into
the disc 62; however, as previously mentioned, other approaches are
also possible. For example, insertion approaches may include a
posterolateral approach, transformational approach, anterior
approach, anterolateral transpsoatic approach, anterior lateral
retroperitoneal approach, and others. Also, while FIGS. 7-11
illustrate placement of only one interbody device 10 in the disc
space 64, it is possible to place multiple interbody devices 10
within the disc space 64 depending on the size and shape of the
interbody device 10. Optionally, as depicted in FIG. 18, the second
filler material 80 can be contained within the interior cavity 19
by including or weaving additional material into the interbody
device 10 to create a barrier such as top and bottom walls 104, 106
that cover the openings in the interior cavity 19. These portions
of the interbody device 10 may be shaped to the shape of the
vertebral endplates.
[0048] With reference now to FIG. 12, one embodiment of the
interbody device 10 is shown following placement and injection of
the first filler material 68 into the annular member 12 and the
second filler material 80 into the interior cavity 19. Therefore,
following placement of the first filler material 68 and the second
filler material 80, the interbody device 10 may provide support to
the spine 81 by maintaining separation of the adjacent vertebrae
74, 76. In one embodiment, the second filler material 80 is a
fusion promoting material that bonds to the endplates 70, 72 of the
adjacent vertebrae 74, 76. In another embodiment, the second filler
material 80 is an elastomeric material that may be more elastic
than the first filler material 68. In an alternative embodiment,
the first elastomeric material may be more than elastic than the
second elastomeric material. By way of example, filling the annular
member 12 with elastomeric materials may allow it to mimic the
natural kinematics associated with a healthy disc. Exemplary
materials include, bioresorbable materials; elastic materials, such
as, polyurethane, silicone rubber, in-situ curable polymer (most
likely an elastomer), and PVA (polyvinyl alcohol) hydrogel; or
other hydrogels, or may comprise poly(lactic acid), poly(glycolic
acid), p-dioxanone fibers, polyarylethyl, polymethylmethacrylate,
polyurethane, amino-acid-derived polycarbonate, polycaprolactone,
aliphatic polyesters, calcium phosphate, unsaturated linear
polyesters, vinyl pyrrolidone, polypropylene fumarate diacrylate,
polymethylmethacrylate (PMMA), bis-GMA polymer, hydrogel
polyurethane, polyacrylamides, a hydrogel or combinations thereof,
or other biologically compatible polymer capable of supporting
axial loads transmitted through the spinal column.
[0049] In another exemplary embodiment, the system may comprise a
dual lumen fill tube 82. As shown in FIG. 13, the dual lumen fill
tube 82 defines a first passage 84 and a second passage 86. The
dual lumen fill tube 82 is inserted into the coupler 14 with the
first passage 84 in fluid communication with the internal volume 18
via alignment of the first and second coupler side holes 24, 26
with a first tube side hole 88 and a second tube side hole 90,
respectively. It will be appreciated that only one of the side
holes 88 or 90 or other opening may be necessary to fill the
internal volume 18.
[0050] The second passage 86 of the dual lumen fill tube 82 is in
fluid communication with the interior cavity 19 via an axial port
92. By way of example only, and not limitation, the first passage
84 may be concentric around the second passage 86. It will be
appreciated, however, that other configurations may be used, e.g.
side-by-side passages. As shown in FIG. 13, the arrows illustrate
flow directions for both the first filler material 68 and the
second filler material 80 into the internal volume 18 and the
interior cavity 19, respectively. In one embodiment, providing the
first filler material 68 and the second filler material 80 may
proceed simultaneously, though the rate of introduction of the
first filler material 68 may differ from the rate of introduction
of the second filler material 80. In another embodiment, the
internal volume 18 may be filled to begin formation of the interior
cavity 19. The second filler material 80 may then immediately
follow once a sufficient portion of the interior cavity 19 has
formed. In yet another embodiment, a proximal end 94 of the dual
lumen fill tube 82 cooperates with the annular flange 32 of the
coupler 14, as previously described with respect to the member fill
tube 28 in FIG. 5 and the cavity fill tube 30 in FIG. 6.
[0051] Another exemplary embodiment of the interbody device 10 is
shown in FIGS. 14, 15, and 16. The annular member 12 of FIG. 14 has
a keel 96 projecting substantially vertically from the annular
member 12. The keel 96 may be formed of the flexible wall 16 and
thus surround the internal volume 18, as shown in FIG. 15. In one
embodiment, the coupler 14 is elongated with a third access point
98. The second and third access points 22, 98 may be positioned on
opposing sides of the coupler 14 to provide access to the interior
cavity 19 adjacent the projecting keel 96. Similar to previously
described embodiments of the annular member 12, the annular member
12 of FIG. 14 is filled with the first filler material 68 through
the first and second coupler side holes 24, 26, for example, when
they are aligned with the first and second tube side holes 42, 44
of the member fill tube 28 shown in FIG. 3, or through the first
and second tube side holes 88, 90 of the dual lumen fill tube 82
shown in FIG. 13. However, the first filler material 68 also fills
the keel 96, for example, through its end opposite the coupler 14,
shown in FIG. 15. The keel 96 may, for example, be a perpendicular
extension of the annular member 12 that expands to project in a
vertical direction. In one embodiment, the keel 96 may partition
the interior cavity 19 into multiple components. As shown in FIG.
15, the interior cavity 19 may comprise sinistral and dextral
portions. Thus, during injection of the second filler material 80,
the second filler material 80 passes out of the coupler 14 into one
of the sinistral or dextral portions of the interior cavity 19 via
the second or third access points 22, 98, respectively.
[0052] With reference now to FIG. 16, the keel 96 may cooperate
with depressions, such as channels 100, formed in the endplates 70,
72 of the vertebrae 74, 76, respectively. Thus, as the first filler
material 68 is injected into the annular member 12, the keel 96 may
expand into one or more of the channels 100. It will be appreciated
that the keel 96 may cooperate with the channels 100 to reduce the
risk of migration of the interbody device 10 from its initial
position. It will also be appreciated that the keel 96 may have
other configurations projecting toward one or both endplates 70,
72. The channels 100 may be machined into endplates 70, 72 prior to
insertion of the interbody device 10 to accept the projecting
portion, such as the keel 96.
[0053] FIG. 17 illustrates another exemplary embodiment of the
interbody device 10. As shown, the annular member 12 is shown in an
expanded state having a plurality of endplate anchors 102. The
endplate anchors 102 may be attached to the flexible wall 16 such
that they may contact adjacent vertebrae. Thus, as the annular
member 12 expands with the first filler material 68, one or more of
endplate anchors 102 may then contact one endplate 70, 72 of the
adjacent vertebra 74, 76. By way of example, the endplate anchors
102 may be natural or synthetic bone, a porous metal such as
TRABECULAR METAL.TM. sold by Zimmer Spine, Inc. of Edina, Minn., or
other compatible material that is osteoconductive. The endplate
anchor 102 may also provide additional frictional engagement of the
interbody device 10 with one of the endplates 70, 72, which may
stabilize the annular member 12 for subsequent injection of the
second filler material 80.
[0054] While the present invention has been illustrated by the
description of one or more embodiments thereof, and while the
embodiments have been described in considerable detail, they are
not intended to restrict or in any way limit the scope of the
appended claims to such detail. Additional advantages and
modifications will readily appear to those skilled in the art. The
invention in its broader aspects is therefore not limited to the
specific details, representative apparatus and method and
illustrative examples shown and described. Accordingly, departures
may be made from such details without departing from the scope of
the general inventive concept.
* * * * *